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By Malcolm Ross

Asbestos crystallizes within rock formations undergoing intense deformation characterized by folding, faulting, shearing, and dilation. Some of these conditions have prevailed during formation of the taconite iron ore deposits in the eastern Mesabi Iron Range of Minnesota. This range includes the Peter Mitchell Taconite Mine at Babbitt, Minnesota. The mine pit is over 8 miles long, up to 1 mile wide. Fifty three samples were collected from 30 sites within areas of the pit where faulting, shearing and folding occur and where fibrous minerals might occur. Eight samples from seven collecting sites contain significant amounts of ferroactinolite amphibole that is partially to completely altered to fibrous ferroactinolite. Two samples from two other sites contain ferroactinolite degraded to ropy masses of fibers consisting mostly of ferrian sepiolite as defined by X-ray diffraction and TEM and SEM X-ray spectral analysis. Samples from five other sites contain unaltered amphiboles, however some of these samples also contain a very small number of fiber bundles composed of mixtures of grunerite, ferroactinolite, and ferrian sepiolite. It is proposed that the alteration of the amphiboles was caused by reaction with water-rich acidic fluids that moved through the mine faults and shear zones. The fibrous amphiboles and ferrian sepiolite collected at the Peter Mitchell Mine composes a tiny fraction of one percent of the total rock mass of this taconite deposit; an even a smaller amount of these mineral fragments enter the ambient air during mining and milling. These fibrous minerals thus do not present a significant health hazard to the miners nor to those non-occupationally exposed. No asbestos of any type was found in the mine pit. © 2007 Elsevier Inc. All rights reserved. Keywords: Taconite; Asbestos; Amphibole; Reserve mining; Tailings; Mesabi iron range; Mineral fibers

Jan 1, 2007

By Adil Aledresse, Louis Mercier, Laxman Amaratunga

"The development of high capacity adsorbents with uniform porosity denoted, MP-HMS (Mercaptopropyl – Hexagonal Mesoporous Structure) using nanotechnology, and their ability to extract gold from solution, is presented. The preparation of highly effective heavy metal ion adsorbents by the incorporation of thiol moieties into the pore channels of mesoporous silica molecular sieves has been the subject of many nanotechnology research investigations. The unique feature of these nanoporous adsorbents is their ability to adsorb gold ions from ultra-low concentration solutions like mine effluent as well as from leached solutions in gold mills. The preliminary studies from laboratory simulated gold solutions show that the adsorption capacities of these materials are also among the highest reported. MP-HMS has shown the capability to adsorb 370 mg gold per one gram of the nanomaterials from Tetrachloroaurate solution (up to 37% of their weight). Experimental studies indicated that the maximum adsorption of gold (as high as 99.9% recovery). The current studies will be extended to investigate the interaction of ionic gold complexes with nanomaterials. Future development of this work may lead to either to replace the conventional CIP/CIL processes or use nanomaterials in tandem with the former, suggesting plausible use of mesoporous material in pulp, MIP or in leach, MIL, as a novel gold extraction process.INTRODUCTIONGold typically occurs at very low concentrations in ores less than 10 g/t or 0.001% (mass basis). At these concentrations the use of aqueous chemical (hydrometallurgical) extraction processes is the only economically viable method of extracting the gold from the ore. Typical hydrometallurgical gold recovery involves a leaching step followed by the separation of the gold bearing solution from the residues, or adsorption of the gold onto activated carbon adsorbent. After elution from the activated carbon the gold is further concentrated by precipitation or electrodeposition."

Jan 1, 2008

By R. W. Bee

This project, sponsored by the U.S. Bureau of Mines, Division of Environment, addresses two major subjects: refuse removal and subsidence monitoring. The refuse removal task consisted of developing a methodology for selecting the most economical combinations of coal mine breaker refuse and rock banks, disposal sites and material moving systems (trucks, trains, belt conveyers and pipelines). To prepare plans for moving refuse in the Lackawanna Valley of Northeastern Pennsylvania, refuse banks were inventoried, underground disposal sites identified and unit cost data prepared for the various material moving systems. The subsidence monitoring task consisted of defining the phenomenon of coal mine induced surface subsidence, establishing operational requirements, cataloging sensors and techniques to detect and measure subsidence and testing of the most promising techniques (photoelastic patch, tiltmeter, strain gage, microseismic and precise surveying). A preliminary system for a 700 acre area in Scranton utilizing 267 grid sensors, seven microseismic sensors and precise surveying techniques was designed with initial and annual operating costs determined. Two minor tasks supported both main subjects: zoning in the Northern Anthracite Field of Pennsylvania and Technology Transfer of subsidence vulnerability prediction techniques.

Jan 1, 1972

By Donald James Butler

Problems resulting from underground mines in three inactive mining districts in Colorado were investigated. The purpose was to determine how these problems could be reduced or eliminated in new closings -- essentially by benefitting from lessons of the past. Mines in Leadville, Westcliffe and the Cripple Creek-Victor districts were evaluated. Two basic types of problems were found to exist in the districts: environmental degradation and hazardous conditions. Environmental problems result largely from acid and toxic drainage from the runes and from leaching of surface waste rock piles and mill tailings impoundment. The acid drainage contributes high levels of metals to streams and deposits sediment in the stream bottoms. Erosion of waste piles is a lesser problem. Hazardous conditions from open or improperly sealed mine shafts and adits, mine subsidence pits, and from deteriorating and unsafe surface structures are common to the three districts. These problems become worse with the ravages of time and vandalism. Engineering solutions which would correct or reduce many of these problems are presented. These recommendations should also be applied to new mine closures, however, more basic changes are needed to effectively implement improved mine closures. The changes must take place in the areas of legislation, mining practices and education. Legislated regulations should realistically reflect the needs of both the mine operators, protection of the environment and the best interest of the general public. Benefits should be provided for compliance with regulations instead of penalties being assessed for noncompliance. Hazardous conditions and environmental problems associated with mines can be alleviated through improved mine design and effective cloning procedures. Education should provide an appreciation by the general public of past and present problems facing mine operators. This will result in an improved mining climate which, in turn, will insure a continuing supply of minerals to meet increasing needs.

Jan 1, 1983

By Ryo Sasai, Takeshi Itakura, Haruki Imaizumi, Hideaki Itoh

"Emission of industrial wastewater containing harmful oxoanions is one of the serious problems on account of its toxicity and the environmental pollution, especially caused by boric, phosphinic, arsenic and antimonic species. In this study, we developed a novel treatment technique of such polluted-water by hydrothermal mineralization. The treatment is “Geomimetic” method for precipitating oxoanions in aqueous media as natural ore resources by using hydrothermal treatment with calcium salts mineralizer. The treatment made it possible not only to detoxify the polluted-water, but also to recover the calcium minerals such as Ca2B2O5·H2O, Ca5(AsO4)3(OH), etc. Concentration of each ion in treated-water was lower than that of effluent standard in Japan. Moreover, the residual concentration of each ion was independent of the initial concentration, but it depends only on the solubility of the formed mineral under hydrothermal condition. Therefore, the hydrothermal treatment could be recommended as one of the treatment techniques of polluted-water.IntroductionVarious oxoanions such as boron and arsenic oxo-anions have high toxicity against human health and the environment. They are important resources, however, for plating or advanced material manufacturing industries[1-3], from which the wastewater containing these oxoanions is generated every day. An appropriate treatment is often required for industrial wastewaters to attain national effluent standards of Japan (NESJ, B: 10 mg/dm3, As: 0.1 mg/dm3). On the other hand, there is no production of arsenic and boric resources in Japan, and they are expected to be recycled. Therefore, the establishment of a system for the removal and recycling of arsenic and boron from wastewaters is of global significance.Several methods to remove them from aqueous media have been already reported by using adsorption[4], electro-coagulation[5], membrane separation[6-8] and biological techniques[9]. However, these methods have the following problems because of their stability in water. (1) Removal yield is low, especially for tri-valent arsenite ion (AsIIIO3 3-) and borate ion. (2) The applicable concentration range is narrow. In addition, the used adsorbents or collected residues after treatments are sill hazardous wastes, so that they must be treated by a proper method. But, it is very difficult to convert them to recyclable resources at most industrial plants. These problems are caused by the difficulty to recover these oxoanions as stable solid precipitates with low solubility in water. The establishment of recycling system of these hazardous compounds will be one of the world-important issues, especially, in Japan, which is poor in natural resources. On the other hand, compounds that contain high arsenic concentrations and are insoluble in water, are often found in natural minerals, for example, as haidinglite (Ca(AsO3OH)·(H2O) or Johnbaumite (Ca5(AsO4)3(OH)). This fact suggests that nature has an ability to produce insoluble As-bearing minerals. Similar phenomena can be found in case of boron, antimony, etc."

Jan 1, 2008

By Michael Rieber

Mineral economics interfaces the mineral sciences and engineering with finance and economics in the analysis of appropriate questions facing the minerals and energy industries. Its practitioners include those trained in the earth sciences; mining, petroleum, and geological engineering; metallurgy and mineral preparation; as well as finance, information systems, economics, and statistics-most usefully in one or more combinations. Allowing for some overlap, three general areas may be identified: evaluation, economic analysis, and resource appraisal. Evaluation begins with mine investment analysis (exemplified by Gentry and O'Neil, 1984) and process costing, for which the STRAMM Handbook (Anon., 1977) provides a well-known basis for mining and beneficiation. But it extends from property appraisal, often used for the determination of taxes and royalties, through the determination and comparison of transport costs (e.g., Richer and Soo, 1977), and to benefit/cost analyses of externalities. Economic analysis, the subject of this section, is displayed in rigor and extent both theoretically and as applied to commodity classes in Vogely (1985), but it is implicit though apparent throughout Lefond (1983). The text edited by Vogely places minerals in their aggregative context with economic growth and trade, proceeds to the theoretical analysis of minerals and their markets, analyzes the structure and performance of the major mineral sectors, and concludes with policy issues: fuel, nonfuel, and environmental. Resource appraisal employs quantitative methods for the estimation of mineral and energy resources. It moves through geologic, geophysical, and geochemical properties to the identification of estimation procedures for mineral endowment and for the economic measure of stocks and flows of specific minerals (Harris, 1984). It can be used to estimate the probable amount of a specific resource remaining in a given region and has been used to project sites in a specific

Jan 1, 2008

By Robert H. Peters

This U.S. Bureau of Mines report identifies the types of serious accidents that occur most frequently at small underground coal mines and describes the strategies that could help prevent these accidents. A wide variety of methods for improving safety are suggested, including improvements in the design of equipment, work procedures, work schedules, safety programs, and emergency response plans, as well as techniques for diagnosing the potential hazards associated with new technologies and work procedures. Some of the papers in this volume focus on preventing specific types of mining accidents--ones associated with materials handling (primarily back injuries), equipment maintenance, improper machine guarding, and ground failure during retreat mining. Although the recommendations in this volume are heavily influenced by research performed at underground coal mines in the Appalachian coalfields, most of the papers contain advice that is equally pertinent to almost any type of mine.

Jan 1, 1994

By Eugen Gluck, Gus Van Weert, Peter Kondos

"Microwaves have the capability to heat up sulphides, especially clusters of particles of approx. 1 mm. Some sulphides absorb microwaves more readily than others. Molybdenite is especially effective in this regard, possibly due to its flaky nature and/or electrical conductivity. Even where it occurs in low concentrations in a deposit, individual rocks may be ore grade due to the high monetary value of MoS2. Such rocks often result from crushing mined veinlets or stockwork, or are contained in the cutoff grade fraction of ROM. Machine segregation of rocks high in MoS2 by infrared sensors after microwaving could therefore advantageously be used to upgrade lower grade ore between Mine and Mill. This would reduce the size of the latter, and thus its CAPEX and OPEX. Such upgrading could also yield shipping ore for a distant Mill, or extend ore reserves.Barrick Gold Corp. has been supporting the development of MW/IR sulphide sorting for the past three years. The results of MW/IR sorting work on molybdenite and other (pyritic) ore samples from a variety of sources are being presented here.INTRODUCTIONThis paper looks at mechanized, i.e. machine ore sorting technologies currently available and under development, and what conditions would be needed for the potential application of such ore sorting to sulphide mining and milling. Current machine sorting involves no-contact sensing technology for rocks, and signal processing after sensing to activate airblast segregation of certain rocks, normally the smallest mass to keep compressed air costs down.The forerunner of modern sorting is probably magnetic separation, which utilizes an inherent property of certain ores to divert it into mag and non-mags fractions. Radiometric ore sorters, which have been applied successfully for decades in the pre-concentration of uranium ores (Wotruba and Riedel, 2006) initiated modern sorting. In the 90’s, sensor-based machine sorting became a viable means of increasing the overall economic recovery of a resource. This technology became driven by the availability of low cost computing equipment and the concurrent development of algorithms, and by the availability of extremely fast response sensors and air actuators, allowing the sorting equipment to run faster, dropping the cost per tonne. It has been in industrial minerals processing that rock sorting has been most widely adopted, not really surprising. Liberation occurs on a different scale than in the base metal industry. Most industrial minerals are mined from massive deposits, requiring (in the past) no upgrading. Many of these operations now run into product contamination problems, which ore sorting can solve. One illustration: in Finland, a quarry is separating limestone from dolomite at 500 tonnes / hour, with individual rocks weighing up to 15 kg. Many of these industrial minerals operations have stockpiles of earlier discarded below-quality rocks, now being reprocessed with the help of ore sorting. The economics of this are very favourable, going from zero or negative value (stockpiles can not be left when closing the mine) to full product value for at least a portion of the stockpile. This suggests that in the future the economics of overburden sorting could become attractive under the right circumstances and such treatment could well become an integral part of open pit mine development."

Jan 1, 2009

By Tapiwa Chenje, Victor Olivas, Peter Radziszewski

"Ore breakage and grinding media wear have always been considered and determined separately in laboratory tests. However the two processes are linked with the ore broken down in any comminution device being responsible for the majority of the steel wear experienced. The Comminution Dynamics Laboratory (CDLab) successfully developed a test methodology that can more accurately predict grinding media wear in tumbling mills than the Bond Abrasion test. This paper looks at the possible application of the abrasive wear methodology to determine breakage parameters of the same ore used in the abrasion test. Results indicate that breakage parameters comparable to t10 can be determined using the Steel Wheel Abrasion Test (SWAT), while using significantly less ore than standard breakage tests.BACKGROUNDThe Rubber Wheel Abrasion Test (RWAT) is an internationally accepted and widely used method for determining the abrasion wear behavior of materials. The abrasion wheel test was developed to primarily utilize a steel wheel (Brinell, 1921). Haworth (1949) criticized using of the steel wheel by arguing that increasing the contact area size in the steel wheel test causes a change in the wear rate with time. He suggested that the use of a rubber wheel instead eliminates this problem, leading to the adoption of the RWAT which was standardized in ASTM G65 (2004).Radziszewski (2002), however, found that the use of the Steel Wheel Abrasion Test (SWAT) was more applicable for wear testing in the mining industry for two critical reasons. Firstly, the major cause of wear in a ball mill, the most frequently used comminution device, is ball-ore-ball contact and also ball-ore-liner which both are metal-ore-metal contact. Therefore, using the steel wheel has the advantage of providing a similar abrasive environment to the one that takes place in a real ball mill. Secondly, the SWAT creates the potential of running experiments at much higher force regimes that are closer to what happens in actual mills, unlike the RWAT which is a low stress test."

Jan 1, 2011

By Tapiwanashe Chenje, David Hewitt, Peter Radziszewski

"Steel media wear is a major cost component in mineral processing. In the case of existing operating mill, steel media wear prediction can be used to help compare the performance of steel media from different suppliers before completing marked ball tests. It can also be used to investigate how ores from different site of a given mine affect steel media wear. In the case of Greenfield cases, steel media wear prediction can be used to estimate the cost of steel media for a given feasibility study.This paper presents a wear testing and prediction methodology that ties together abrasion wear and corrosion wear testing results through the use of a simplified discrete element charge motion model. The experimentation dimension to this methodology takes samples for steel media, mine site ore and water to determine abrasive and corrosive wear parameters of a given media, ore, water set.The test methodology development is illustrated along with a comparison of wear predictions with observed wear rates in some operating mills. A case study is included that illustrates how this methodology was used to estimate steel media wear performance. The paper closes with a discussion on the use of parts of the experimental methodology to investigate other abrasive wear conditions such as liner wear, paste backfill piping and ore breakage as well as avenues for future test development.INTRODUCTIONThe cost of comminution processes represents a significant part of the overall costs of a mining operation. Grinding media/liner wear alone accounts for 15-25% of the total operating cost. The annual steel grinding media consumption is approximately 2.5 mtpa or 0.3% of total world steel production [Smorgon Steel Group, 2005]. Using an estimated grinding media cost of about US$0.75/kg [Halbe and Smolik, 2002], gives a media cost of over US$1.875 billion per annum. Mining continues to shift towards exploitation of lower grade ores as the higher grades get depleted. These low-grade ores require finer grinding for the liberation of the value minerals, and hence it can be assumed that grinding media consumption will also continue to rise.The Bond abrasion test, dating back to 1963, [Weiss, 1985] is still used to estimate the total mill media wear. This is a purely empirical test based on the ore. From Bond abrasion index tests, it is possible to determine a wear rate using the following function:"

Jan 1, 2009

By Rodolfo Espinosa

"Industrias Peñoles, S.A. de C.V. in Mexico, has nine mining operations, six managed by Peñoles (base metal mines) and three managed by Fresnillo plc (precious metal mines). Seven of the operations use flotation and the other two are heap leach operations, one for gold and the other one for copper.This paper gives a brief introduction of Peñoles, shows mine locations and describes the main process characteristics of each concentrator. It also presents four of the new operating practices that were implemented over the last four years to improve the economics of the mining operations. These include (1) the use of centrifugal gravity concentrators to increase the recovery of gravity recoverable gold (GRG) and silver (GRS), (2) the use of expert systems to reduce process variability while increasing grades and recoveries, (3) the application of the Six Sigma methodology to key projects to ensure success and personnel development and (4) the use of water chemistry fundamentals to identify chemistry problems and design adequate solutions for improving grades and recoveries.INTRODUCTIONPeñoles was founded in 1887. It is a mining group with integrated smelting, refining and chemicals producing operations. Peñoles is the world largest producer of refined silver and metallic bismuth, the leading Latin American producer of refined gold and lead. It is amongst the world leading producers of refined zinc and sodium sulfate.Peñoles operates and controls six underground mines in Mexico and is the largest producer of zinc and lead of the country. It also produces copper concentrates and cathodes. Through its 77.1% equity stake in Fresnillo plc (a London Stock Exchange listed company); Peñoles is also a significant producer of gold and silver. Fresnillo plc operates three precious metal mines in Mexico. While Fresnillo is the world largest primary silver mine, Ciénega and Herradura are two leading gold mines of Mexico. Figure 1 shows a map of Mexico indicating the locations of the Peñoles mines. The main process characteristics of each concentrator are listed in Table 1."

Jan 1, 2011

By Howard E. Parkinson

In 1969, new coal mine health and safety legislation was enacted in the United States. As a result of this legislation, the Department of Interior, Bureau of Mines has carried out communications research aimed at developing whole mine communications for increased safety and efficient operation. The research has advanced and many promising results are now being demonstrated to the mining industry. However, there remains a challenge to further improve wireless communications within the mine workings and through the overburden above the workings. The objectives for future research and development will be discussed, together with the physical and operational constraints that new mine communication systems must face.

Jan 1, 1973

By Northcutt Ely

This volume summarizes mining and petroleum legislation in 30 jurisdictions of the Western Hemisphere. Within these jurisdictions, primary attention is given to requirements that must be met in each country for acquisition of rights to permit development of mineral resources. Coverage includes: First, identification of the controlling laws or statutes governing minerals acquisition and reference to the administrative authority; second, analysis of the laws governing mines and quarries and their products; and third, analysis of laws applicable to natural gas, petroleum, and related materials. Where pertinent, sections dealing with historical background or administration have been added. In countries where minerals are subject to control of States or Provinces, those areas are considered separately from the central government.

Jan 1, 1970

The Bureau of Mines studied available information on the nature and occurrence of potential sources of aluminum in the United States, its Pacific island possessions, and Puerto Rico to obtain data for use in evaluating the production capability and costs of extracting the aluminum from such materials. The quantity, type, and grade of the materials range from 4 billion tons of bauxite, bauxitic clay, and kaolin averaging 33 to 42 percent Al2O3 to nearly 600 billion tons of anorthosite containing only 27 percent Al2O3. Principal deposits of bauxite, bauxitic clay, and kaolin occur in Arkansas, Georgia, Hawaii, and Oregon. Major anorthosite deposits are located in New York, Wyoming, California, Idaho, and Montana. About 11 billion tons of material in deposits of various types of clay, the kyanite group of minerals, laterites, and shales averaging 27 to 30 percent Al2O3 comprise additional resource's from which aluminum some day may be extracted. Material meeting specifications of the study was found in only 22 States and the Pacific island possessions. Utilization of these large low-grade sources of aluminum awaits development of processes that are economically competitive with the Bayer process for extracting alumina from baxuite, which is at present the only commercial ore of aluminum. Changes in economic and political conditions also may play important roles in the eventual development of the potential sources of aluminum.

Jan 1, 1967

By M. Jaffe

The data developed in this study establishes the technical and economic feasibility as well as the improved health and safety characteristics of a novel mining concept. The mining concept is a modified longwall technique using prestressed tendons for roof control, longhole blasting for fragmentation, and remote mucking. The technical feasibility was found to be dependent on the state of the art, while economic feasibility was found to be dependent on particular minerals and on supply and demand. Since these two conditions are not necessarily coincident in time the data is presented in the report in a manner that enables the mining engineer to perform a rapid preliminary technical and economic analyses for a specific property.

Jan 1, 1977

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigations beginning with No. 4251, of which this is the third. The data are accompanied by maps showing the location of holes drilled and deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township-map. The description of each half township is followed by a description of each deposit developed in that half township.

Jan 1, 1948

By A. Stawsky

Effective use of diesel vehicles in underground mining requires attention to improved control of diesel exhaust pollutants such as particulate (soot), oxides of nitrogen and sulfur and carbon monoxide. An experimental survey Is made of diesel emission aftertreatment control techniques including water scrubbers, catalytic converters, exhaust gas recirculation (EGR) and soot filters. Use of two or more techniques in combinations are tested for optimum control of all exhaust pollutants. Dynamometer data is developed for steady state and computer controlled simulated mines duty cycles operation of Deutz F6L-714 and F8L-413 engines. Exhaust Quality indices (EQIs) are calculated from dynamometer data for comparisons among the control combinations examined. The Corning diesel particulate filter (DPF) is shown to be the most promising and practical device. The Corning DPF in combination with EGR provided the best (lowest) EQI from the test data. Use of the DPF requires additional regeneration mechanisms such as a catalytic filter coating or fuel additives. A metal mine field test is made of DPFs on an operational scoop tram to test practical applicability. Further development is proposed for application to various mine conditions and for improvement of DPF regeneration techniques including coating with newly available catalysts.

Jan 1, 1987

By A. S. Watts

The Bureau of Mines has been conducting an investigation of the feldspar resources of the New England and North Appalachian States with a view to greater efficiency and economy in their utilization. Such an investigation was deemed necessary, not only because of the continued and increasing consumption of these minerals, but especially because of the demand for better technical control of the raw materials that are used by the white-ware industries of the United States. Most manufacturers of white pottery wares have only a limited knowledge of the origin, mode of occurrence, and methods of mining and preparation of the materials that they use. Heretofore, owing to a belief that the supply of raw material was unlimited, the manufacturer had concerned himself chiefly with the solution of the problems of manufacture. Within the past few years, however, it has been found that difficulties arise in manufacture which can be traced beyond the manufacturing process and are believed to be due to a need of better control of the materials used. Furthermore, as competition becomes more severe, more attention must be paid to selection of materials in order to minimize consumption and also to avoid unnecessary expense for transportation of material. Doubtless the lack of interest as regards these details has arisen from the fact that in the past a considerable proportion of the whiteware ingredients has been imported and the manufacturer has been forced to rely on the samples submitted and the general uniformity of the source of supply to insure against variation of the material. An extra precaution arising from this lack of definite knowledge still prevails in the common practice of never depending on one source of supply for anyone ingredient. Often the products of three or more producers are blended so that if anyone shall vary without warning the variation arising from its use will not be sufficient to ruin the ware.

Jan 1, 1916

By Elaine T. Bowers

The Sunnyside single-entry project pioneered the use of single entries for longwall development in this country. During the 10-year course of the project, an immense amount of information was gathered. Over three miles of entries were observed primarily through instrument groupings placed in strategically located areas or "rooms." Nearly 1,200 instruments were monitored to gain information on the behavior of coal entries during development stages and through the mining of two longwall panels. This was one of the most extensively documented projects undertaken by the Bureau, The data gathered has a great potential for scientific research especially in the area of longwall mining. This Bureau of Mines report presents the ground control data gathered, in the form of computerized plots. Roof-to-floor deformation and load on cribs and roof bolts make up the bulk of the data, which is presented as load or deformation versus time. The plots are organized, generally, by the three main entries involved and, specifically, by the individual areas or rooms in those entries. No major attempt will be made, in this paper, to analyze the data other than to identify its source arid its history.

Jan 1, 1983

By Lyman Moore

This Bureau of Mines report describes 2nd evaluates iron ore resources in California and Nevada and analyzes the California and Japanese iron ore markets in which these resources will be used. The competitive position of California-Nevada ores, in these markets, was estimated by comparing regional iron ore prices, production costs, and transportation costs with those of foreign suppliers. Resources were determined to be sufficient to produce the equivalent of 585 million tons of 64-percent iron pellets at a price of less than $15 per ton delivered at California ports. Much higher tonnage could be produced at higher prices. Iron ore requirement of the California iron and steel industry will increase to an estimated 15.9 million tons by the year 2000. A study of the iron ore production potential of California-Nevada deposits and of out-of- State sources indicated that this ore requirement can be supplied most economically by California-Nevada ores. Iron ore import requirements of the Japanese iron and steel industry will increase to an estimated 150.0 million tons by the year 2000. A study of price trends in this market indicated that very little California-Nevada iron ore will be sold in Japan after 1973 when existing sales contracts expire. Iron ore-exports might be economically possible if ore could be transported from California to Japan at ballast rates as backhaul on existing petroleum shipping.

Jan 1, 1971